1. Field of the Invention
The present invention relates to an interior illumination device mounted on an interior of a vehicle.
2. Description of the Related Art
Generally, an interior illumination device is mounted on a ceiling of a vehicle. Japanese Published Patent Application No. 2005-329884 discloses a conventional interior illumination device. As shown in FIGS. 11A and 11B, an interior illumination device 10 includes a design part 20 and a functional part 30. A ceiling board 40 is interposed between the design part 20 and the functional part 30. A switching knob 21 is swingably supported by a first swingably supporting part 22 in the design part 20. An engaged part 23 is formed in a concave shape at a rear side of the switching knob 21. Further, a switching lever 31 is swingably supported by a second swingably supported part 32 in the functional part 30. An engaging part 33 is formed in a convex shape at the second swingably supported part 32 of the switching lever 31.
When the design part 20 and the functional part 30 are assembled on the ceiling board 40, the engaging part 33 is engaged with the engaged part 23, and the switching lever 31 is swung in conjunction with an operation of the switching knob 21. When the switching knob 21 is operated, a not-shown electric circuit is switched by the switching lever 31, and a not-shown bulb of the interior illumination device 10 is lighted to illuminate an interior of a vehicle.
However, in the interior illumination device 10, because the switching knob 21 attached to the design part 20 is swingably supported by the first swingably supporting part 22, when an external force is applied to the switching knob 21 at a transportation of the interior illumination device 10, the switching knob 21 may be rotated to a position (angle) where the design part 20 and the functional part 30 are not allowed to be assembled with each other. In this case, it is necessary to return the switching knob 21 to a position where the engaging part 33 and the engaged part 23 are allowed to be engaged with each other. Therefore, assemblability of the design part 20 and the functional part 30 may be reduced.
Therefore, for preventing the switching knob 21 from rotating excessively with the external force, fitness between a main body of the design part 20 and the switching knob 21 at the first swingably supporting part 22 may be solid. However, in this case, operability of the switching knob 21 is reduced.
Accordingly, an object of the present invention is to provide an interior illumination device of which assemblability is improved.